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Motion Mania: Applying Physics to Hula-Hooping

google science journal hula hoop physics  
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Project with Your
works with google science journal app
Areas of Science Physics
Science With Your Smartphone
Time Required Short (2-5 days)
Prerequisites You should know how to (or be willing to learn to) hula hoop around your waist or arm. Note: Hula-hooping is fairly easy if you have the right hula hoop for your body. This science project provides guidelines to make such a hula hoop.
Material Availability Readily available.
Cost Average ($40 - $80)
Safety Adult help is required to cut the tubing to make your own hula hoop.


Practice makes you better at most things, and knowledge makes practice so much easier! Can you swirl a circular toy called a hula hoop around your waist or arm? Is it hard? What knowledge can you apply to find ways that make hula-hooping easier? Physics! Yes, physics will help you determine what makes one hula hoop a winner and another a flop. In this project, you will create your own hula hoops, spin them, and draw conclusions. The road will then be open to your becoming a hula hoop expert. If you have a smartphone available, you can use it to measure how fast you hula hoop with Google's Science Journal app.


To make hula hoops of different circumference and mass and study how these factors affect the speed at which the hula hoop spins around.

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Sabine De Brabandere, PhD, Science Buddies
Edited by Ben Finio, PhD, Science Buddies

Cite This Page


MLA Style

Science Buddies Staff. "Motion Mania: Applying Physics to Hula-Hooping." Science Buddies, 13 Mar. 2020, https://www.sciencebuddies.org/science-fair-projects/project-ideas/Phys_p088/physics/hula-hooping. Accessed 3 June 2020.

APA Style

Science Buddies Staff. (2020, March 13). Motion Mania: Applying Physics to Hula-Hooping. Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/Phys_p088/physics/hula-hooping

Last edit date: 2020-03-13


Have you ever spent time spinning a hula hoop on your waist or arm? Have you ever wondered how hula hoops work? This science project will not only teach you how to make a hula hoop, but it will also guide you in finding the hula hoop that is right for you and describe the physics that make a hula hoop spin. Add a little spinning creativity and practice, and you could become a hula hoop expert!

How can physics help you become a better hula hooper? (Hula hoopers are often referred to as "hoopers.")

Note: While you can hula hoop using various parts of your body, this project focuses on traditional waist hooping. After finishing this project, you could extend your exploration to arm or leg hooping.

Before we analyze what makes the hula hoop spin, let's think about how we can measure the spinning motion of the hoop. Any ideas? Would the speed, or how fast the hula hoop spins, be a good factor to measure? If so, how would you do it? (In this project, you can use as stopwatch or Google's Science Journal app to measure the speed as the number of times the hula hoop or your hips make a full turn per minute.)

Now, think about what makes the hoop spin. When hula hooping, you are the source of the hoop's movement. When you move your body to propel your hoop around you, you are actually exerting an upward force (from your hips) to keep the hoop from falling down. You also exert a torque, or a twist, to keep it spinning. While forces act in straight lines (like pushing on a box or pulling on a rope), torques make things rotate, like twisting a doorknob or a screwdriver. For hula hooping, the amount of force needed to keep up a good spinning motion depends upon the weight and mass of the hoop, the size of the hoop, and how well the hoop fits around your waist.

Weight and mass? Are these not the same? No. Even though they are closely related, weight and mass are different. Mass is a measure of how much matter, or "stuff," an object holds. It is expressed in kilograms (kg) or grams (g) and is a measure of how easily the object reacts to a force. Say we have a 2000 kg car and a 100 g (or 0.1 kg) toy car. If you give both the same push (a scientist would say "you apply the same force to both objects") to get each to move forward, which one will react quickest and move fastest? Once they are both in motion, which toy car will be easiest to stop when applying the same force to both? The one with a lot of mass or the one with a small amount of mass? A lot of mass needs a lot of force to make its motion change (for instance, slow down or speed up). How would this apply to your hula hoop? Would a heavy hoop react strongly or just a little to a small push? Would it have a greater or lesser change in speed?

If mass is a measure of "the amount of stuff," what is weight? Weight is a force and is measured by how strong the planet you are on (e.g., the Earth or the Moon) "pulls" the object toward itself. A hula hoop has the same mass here on Earth as on the Moon because it consists of the same amount of material. The weight of the hula hoop, on the other hand, is greater on Earth than on the Moon because the force of gravity is stronger on Earth than on the Moon, so the Earth pulls harder on the hula hoop than the Moon does.

We cannot go to the Moon or any other planet to practice with our hula hoops, but weight still plays a role in hula hooping. How? Do you think a hula hoop with more mass will be pulled more strongly toward Earth than a hula hoop with less mass? Think of the car: Does a loaded toy car (loaded means more mass) feel heavier than an empty one? The feeling of "heavy" is the Earth pulling more strongly on it. So more mass (more stuff) does mean more weight (a stronger pull of the planet). Because a more massive hula hoop is heavier, it will tend to fall down more rapidly. What can a hula hooper do to prevent the hoop from falling? The hooper needs to give the hoop a stronger push up to overcome its weight (or to balance the force pulling the hoop down, as a scientist would say).

So far, we have the weight pulling the hoop down, our body giving it a push up to prevent it from falling, and torque giving the hula hoop a spin. So will it spin forever? Is there anything slowing down the turning motion? Think for a minute: If a ball is rolling, does it roll forever? No, of course not, but what stops or slows the ball down? Friction stops the ball. The ball slows down (or decelerates) because of friction between the ball and the air surrounding it and between the ball and the surface it rolls on. The same is true for the hula hoop. Because of friction, you need to periodically give the hoop a little boost, or torque, to overcome the friction that stops the hoop from turning and keep it spinning. At the same time, friction also works against gravity to help keep the hula hoop up on the hula hooper's body. Friction is not always a bad thing—think about trying to walk on ice—walking is very difficult without friction!

We still need to explore one more important aspect, the size of the hoop and its effect on speed. Would a big hoop (larger circumference) turn around your body slower or faster than a small hoop? If the question seems difficult, maybe exaggerating will help provide the answer. Would a hoop that is much bigger than your waist take more time to make a full turn around your waist than a hoop that barely fits around you? It is easy to visualize that it will take more time for the larger hoop to make a full turn than the smaller one. This means that the larger hoop has less speed than the smaller hoop.

Now that we have explained it all, let us review what we have learned:

  • Weight pulls the hoop down. The hula hooper prevents the hoop from falling down by exerting an upward force and a torque to make it spin.
  • Friction works to slow the hoop down, and the hula hooper needs to prevent this by applying torque. Friction also works to keep the hoop up.
  • The greater the mass of the hoop, the greater the weight and the more the hula hooper needs to push for the hoop to react and stay up. The same force or push to a lighter object when applied to a more massive object will cause the more massive object to change its motion (speeding up or slowing down) less.
  • The larger the hoop, the slower it will spin.

Can you put it all together and make a prediction? What would be easier: working with a hoop with more mass or less mass? Working with a bigger or a smaller hoop? In fact, there is no right or wrong answer to this question! What works for one person does not always work for another. This science project challenges you to find what works for you (or your test person). Disappointed? While what works well for one person may not be best for another, science does enable you to make other types of predictions! In this physics science project, you will investigate how the size and weight of a hula hoop affect the speed at which it spins around. Can you predict which of these combinations will turn fastest (or which has the greatest speed)? The small lightweight hula hoop? The heavy, bigger version? The heavy, small hula hoop? Or the lightweight, big hula hoop? Here, there is a right answer! . You can find the answer by doing this hands-on science project. Once you have finished, try to explain your findings by reading the Introduction again.

Now, go and explore! Time to spin into action!

Terms and Concepts

  • Physics
  • Speed
  • Force
  • Torque
  • Mass
  • Weight
  • Gravity
  • Friction
  • Decelerate
  • Diameter
  • Circumference

Optional terms for students using Google's Science Journal to collect data:

  • Velocity
  • Periodic
  • Acceleration
  • Accelerometer
  • Period


  • What forces act on a hula hoop in motion? Which work against hula-hooping and which work in favor?
  • Will a heavier hoop (i.e., one with more mass) rotate slower or faster around your body than a lighter hoop?
  • Will a bigger hoop take less or more time to rotate around your body?


To learn more about Google's Science Journal app, visit the website below:

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Materials and Equipment

  • Polypipe, which is hard, black tubing usually used for irrigation (5/8 inch, 3/4 inch, or 1 inch diameter; 100-foot coil). Available from a garden supply store or home improvement store.
  • Metric tape measure
  • Calculator
  • Sharp cutter knife or PVC cutter
  • Poly insert couplings that fit the size of your tubing (4, same size as your polypipe; for example, 3/4 inch poly insert couplings work for the 3/4 inch tubing). Wooden dowels with a diameter that just fits inside the tubing with a length of about 1 1/2 inch can also work. Both can be found at a garden supply or home improvement store.
  • Hairdryer
  • Wide plastic tape (min. 2.5 cm wide)
  • Optional: Colorful electrical tape
  • Funnel (with an opening that can fit into the polypipe) or 1 sheet of thick paper
  • Cup measure
  • Dinner knife with flat edge
  • Sand (2 cups)
  • Kitchen scale, such as the digital pocket scale from Amazon.com
  • Bucket
  • Timer or stopwatch
  • Helper or person who wants to hula hoop for you
  • Adult helper
  • Optional: A smartphone to record your data
    This project uses Google's Science Journal app, a free app that allows you to gather and record data with a cell phone. You can download the app from Google Play for Android devices (version 4.4 or newer) or from the App Store for iOS devices (iOS 9.3 or newer).
  • See the Collect Data with the Science Journal app section at the end of the procedure for instructions to use the phone in this project.


Experimental Procedure

Note: In this project, you will measure how fast people can hula hoop using different sized hoops. Optionally, you can use a phone with Google's Science Journal app to make a graph of your hula-hooping motion. You can find the instructions to do so here.

Make Your Big, Lightweight Hula Hoop

The directions below guide you in making the large, lightweight hula hoop.

  1. Cut a piece of tubing of the appropriate length.
    1. Measure the height from the ground to the middle of your chest in centimeters (cm) — this will be the diameter (or height of the circle) of the biggest hula hoop.
    2. Calculate the circumference (or distance around the circle) of the hula hoop using following formula:
      Circumference = π x diameter
      Circumference = 3.14 x diameter

      The circumference is the length of tubing you will need to cut to create this hula hoop.
    3. In your lab notebook, make a data table similar to Table 1 and record the diameter and circumference for your two larger hula hoops.
    4. Measure the length (circumference) needed from your roll of polypipe tubing and mark where the tubing should be cut. Optional: you can use a piece of electrical tape to help mark the spot.
    5. Ask an adult to cut the tubing at the indicated spot using a sharp knife or a PVC cutter.
Mass of Added Sand
Hoop 1 (Big, lightweight hoop)  0 g
Hoop 2 (Big, heavy hoop)   
Hoop 3 (Small, lightweight hoop)  0 g
Hoop 4 (Small, heavy hoop)   
Table 1. Record the data about the four different hula hoops in your data table.
  1. Connect the ends of the tubing so they form a circle and join the circle using a poly insert coupling or wooden dowel.
    1. If you are using poly insert couplings or a dowel that is a tight fit, you may need to first use a hairdryer to warm the tubing ends (one at a time), for about two minutes. Heat will expand the tubing, enabling the connector to slide in easily.
    2. Once they can fit inside the tubing, put the poly insert coupling or dowel in one end of the tubing (the one you warmed) till the coupling is about halfway inserted.
    3. Insert the other half of the connector into the remaining free end of tubing. See Figure 1 to help visualize this step.
    4. Push the tubing together until little (or no) coupling is visible. If you are using poly insert couplings, you may have a small ridge of plastic still visible in the middle.
    5. Tip: If it is ever difficult to insert the coupling, try using the hairdryer to warm the tubing more in the area where the coupling appears to be stuck. Warm the tubing for roughly two minutes at a time. You may want to have an adult help you push the coupling inside of the tubing.
Two pieces of tubing are joined by sliding over a small connector piece
Figure 1. This picture shows how to connect the tubing ends to form the hula hoop using a wooden dowel.
  1. Secure the connection. Put some wide plastic tape over the connection where the two ends of tubing meet, as shown in Figure 2.

    Tape is wrapped around a tube to secure where two pieces of tubing meet
    Figure 2. This picture shows how the sealing is secured with wide, brown tape.

    1. Optional: Decorate your hula hoop with colorful electrical tape any way you like . Examples of decorated hula hoops are shown in Figure 3.
Three hula-hoops are individually wrapped in colorful tape and lay on top of each other
Figure 3. Finished hula hoops can be decorated (optional) with different colors of electrical tape.

Make Your Big, Heavy Hula Hoop

Now that you know how to make the bigger size hula hoop, make a heavier version of this hoop.

  1. Cut off a piece of tubing the same length as your Big, Lightweight Hula Hoop. (See step 1 of the first section of this Experimental Procedure.)
  2. Create a funnel that can be used to fill the tubing with sand. Skip this step if you have a funnel that fits in the hole of your tubing.
    1. Cut of a piece of tape (about 5 cm. long) and keep it handy.
    2. Roll the sheet of thick paper into a cone (like an ice-cream cone), leaving a small hole at the end. The hole should be big enough to leave room for sand to flow trough but small enough to fit inside your tubing. Figure 4 shows what the funnel should look like.
    3. Fasten the funnel with tape.
Thick paper is rolled at an angle to create a funnel and taped to hold its shape
Figure 4. Make a funnel from thick paper and tape (blue tape was used to make it visible, but any tape works).
  1. Measure and determine the mass of one cup of sand.
    1. Use the scale to weigh the measuring cup alone (in grams [g]) and record the result.
    2. Scoop up 1 cup (c.) of sand and scrape off any excess sand by pushing the flat side of a dinner knife across the rim of the cup.
    3. Use the scale to weigh the sand and measuring cup together, and record the result. Is this the mass or the weight of the cup with sand?
  2. Fill the tubing with sand.
    1. Have a helper hold one end of the tubing up.
    2. Hold the tubing over a bucket.
    3. Using the funnel, pour the sand into the tubing.
    4. Pick up any spills in the bucket and pour those in the tubing as well.
  3. Finish this hula hoop by following steps 2–3 of the first section.
  4. Calculate and record the actual added weight to the hula.
    1. Does the reading from the scale in step 3c represent the mass added to the hula hoop? Does the cup holding the sand play a role in the reading? Yes it does! Can you find a way to obtain the mass of the sand added to the hoop with the data you obtained? If you subtracted the mass of the cup (the reading you took in step 3a) from the mass of the cup filled with sand (the reading you took in step 3c), you got it right!
    2. Record the mass added to the hula hoop in the data table in your lab notebook in the column "Mass of added sand."

Make Your Small, Lightweight Hula Hoop

Make a smaller hula hoop with approximately the same weight as the big, lightweight hula hoop.

  1. Calculate the length of tubing needed for the smaller hula hoop
    1. If the diameter of the smaller hula hoop is measured from the ground to your navel, can you find the length of tubing needed? (See step 1 in the first section of this Experimental Procedure, "Make Your Big, Lightweight Hula Hoop," for hints.)
  2. Create your small hula hoop using the new calculated length (circumference) of tubing.
  3. Think about how the masses of the two lightweight hula hoops (one big, the other small) compare to each other.
    1. Would the small, lightweight hula hoop be equal in mass to the bigger, lightweight hula hoop? If not — what accounts for the difference?
    2. Can you calculate how much extra tubing goes in the bigger hula hoop with respect to the smaller hula hoop? Remember: You recorded the circumference of the big and the small hula hoops in your data table.
    3. Would the extra tubing in the big hula hoop provide the extra mass? If so, is this extra amount of mass large with respect to the total mass of the hula hoop?
    4. Is it safe to say the two lightweight hula hoops are approximately the same in mass? (Note: You can weigh a small piece (e.g., 10 cm) of tubing and calculate from there how much the hula hoops differ in mass.)

Make Your Small, Heavy Hula Hoop

Make a smaller hula hoop with approximately the same weight as the big, heavy hula hoop.

  1. Create another small hula hoop as described in the previous section ("Make Your Small, Lightweight Hula Hoop"), this time filling it with one cup of sand, following steps 3 and 4 in the section entitled "Make Your Big, Heavy Hula Hoop."
  2. If you enjoy a little challenge, put some thought into how the masses of these hula hoops compare. Without knowing the exact numbers, can you reason which relative mass difference would be bigger — the one for the heavy hula hoops or the one for the lightweight hula hoops?

    Use the following formula to calculate the relative mass differences:

    Relative Mass Difference  =   Mass Big Hoop - Mass Small Hoop
    Mass Big Hoop

    To see which one is bigger, look at how the numerators compare (cross out the symbols that do not fit):

    Mass Big Heavy Hoop - Mass Small Heavy Hoop
    { <

    Mass Big Light Hoop - Mass Small Light Hoop

    Now, how do the denominators compare?

    Mass Big Heavy Hoop
    { <

    Mass Big Light Hoop

    Knowing this, can you make a conclusion about how the fractions compare?

    Mass Big Heavy Hoop - Mass Small Heavy Hoop
    Mass Big Heavy Hoop
    { <

    Mass Big Light Hoop - Mass Small Light Hoop
    Mass Big Light Hoop
  3. As you now know, the relative difference is smaller for the heavy hoops than for the lightweight hoops. Can you safely say the two heavy hula hoops are approximately the same in mass?

Test the Performance of the Different Hula Hoops

Time to put the hula hoops to the test! How? One person will hula hoop, and the other will count how many full turns the hula hoop makes around the body during one minute of hula hooping. You will test all four different types of hula hoops in this way. How do scientists refer to the number of turns per minute? Can you recall it from the introduction? (That is right: It is referred to as "the speed" of the hula.) You will measure the speed of all four hula hoops.

If you need directions on how to hula hoop, check out the introduction on how to hula hoop video:

Before we go into the tests of the hula hoops, we need to introduce some terms. The person who hula hoops will be referred to as the hooper. The other person will help by counting and watching the timer. This person is referred to as the helper. The helper will count the number of times the hoop goes around the arm or waist. This "number" is called the data. The helper will collect data for all four hula hoops. This set of four numbers will be referred to as a set of data. At the end, you will compare or analyze the obtained data and try to draw conclusions.

Can you predict how the speeds of the different hula hoops (or how fast each hula hoop goes) will compare to one another? Which hula hoop do you expect to be fastest? Which one will be next fastest, and so on?

Ready? Here you go:

  1. Decide who will be the hooper and who will be the helper. You can switch roles after a set of data has been collected (see step 6).
  2. Decide whether to take measurements for hooping around the waist or hooping around the arm.
    1. Give it a quick try. Can the hooper spin the four hula hoops in the chosen way (around the waist or around the arm)?
  3. Count the number of turns the hooper can turn this hoop around during one minute.
    1. The helper sets the timer to 1 minute.
    2. The hooper starts hula hooping.
    3. The helper starts the timer as soon as the hooper reaches a steady pace.
    4. The helper counts how many full turns the hoop makes around the body or arm of the hooper.
    5. The helper stops counting as soon as the timer rings. Time for the hooper to take a break.
    6. If the hoop falls before the timer rings, repeat with the same hula hoop from step a. If the hooper is still not able to hoop through the full minute with this hula hoop, don't worry — a failed test can provide valuable information as well. Note the observation in your notebook. If hooping one minute with most hula hoops is too difficult for this hooper, collect a set of data for 30 seconds instead of one minute and/or switch to hooping on another body part.
    7. In your lab notebook, make a data table like Table 2 and write down the number of turns counted for this hula hoop in your new data table.
      1. If the hooper did not reach the full minute but instead spun the hoop for 30 seconds, multiply the number of turns they did in 30 seconds by two to get how many turns would have been done in one minute.
  Results Set 1
(Number of Turns in One Minute)
Results Set 2
(Number of Turns in One Minute)
Results Set 3
(Number of Turns in One Minute)
Results Set 4
(Number of Turns in One Minute)
(Number of Turns in One Minute)
Hoop 1 (Big, lightweight hoop)     
Hoop 2 (Big, heavy hoop)     
Hoop 3 (Small, lightweight hoop)     
Hoop 4 (Small, heavy hoop)     
Table 2. Record the results of the tests in a data table like this.
  1. Repeat step 3 for a different type of hula hoop.
    1. Note: The hooper should not change clothes while collecting one set of data. Why? Because, the friction between the hoop and the hooper's clothing may affect the data. Can we compare data collected under different circumstances?
    2. Repeat this step until all four hula hoops have been tested by this hooper.
  2. Repeat steps 2–4 to collect a new set of data. You can switch roles at this point, or call in a different person to be the hooper.
    1. Do you see why you should not switch roles while taking one set of data, but why it is okay to switch when collecting different sets of data? Would you be able to compare the numbers collected within one set if different hoopers were executing the test?
  3. Repeat step 5 two more times for a total of four sets of data. If you enjoy this testing, go ahead and collect a couple more sets of data. Be sure to keep the same attention and eye for precision.

Analyze Your Data

Now that you have all the data, see what it tells you.

  1. Consolidate the data by calculating the average number of turns measured over the different sets of data collected.
    1. Add the numbers collected across one row (for example, data sets one through four for the big, lightweight hula hoop) and divide by the number of filled columns in that row. For example, if you recorded 60, 80, 65, and 75 as the number of turns for a given hula hoop in one minute, the average would be (60+80+65+75)/4 = 280/4 = 70 for that hula hoop.
    2. Write the resulting average in the last column of your data table.
  2. Analyze the data.
    1. Can you see a clear difference in the number of turns recorded for the different hula hoops? Is one clearly faster or slower than the others?
    2. Is there a clear pattern (fastest / slowest) in each set of data taken? (For example, does each data set show Hoop 1 to be the fastest and Hoop 3 to be the slowest?)
  3. Draw conclusions or explain your observations if possible.
    1. Is there a link between the characteristics of the hula hoop (e.g. mass, diameter) and the speed at which it turns?
    2. If you see a pattern (fastest / slowest), does it match what you thought would happen before you started the testing?
    3. Can you explain why you obtained these results? Hint: If you are having trouble explaining this, try re-reading the Introduction in the Background tab.

Optional: Collect Data with the Science Journal App

What if you wanted to take a more scientific measurement of the motion of your hips or the hula hoop in this project? What could you measure? One thing scientists measure about moving objects is their velocity, or their speed and direction. When you hula hoop, the front-to-back and side-to-side velocity of your hips change over and over again as you rotate your hips. Scientists describe this type of repetitive motion as periodic. A change in velocity is called acceleration. Sometimes it is easier to measure acceleration than velocity. Scientists measure acceleration using a device called an accelerometer. Accelerometers are built into many smartphones and video game controllers to create motion controls. These controls allow games to respond to motion when you tilt or shake the controller.

You can use an app called Science Journal to record data with your phone's accelerometer. To learn how to measure acceleration and how to record data with the app, you can review the relevant tutorials on this Science Journal tutorial page. Then, try out this procedure:

  1. Figure out how to mount the phone to your waist or hip while hula hooping. You could put the phone in your back pocket or use a phone belt clip, but make sure the phone does not interfere with the regular motion of the hula hoop.
  2. Open all four available accelerometers (scroll down in the app and press the "+" button to do more than one measurement at once). You can measure X (side to side), Y (up and down), and Z (front to back) acceleration individually, as well as the linear acceleration. Note that the X, Y, and Z directions are relative to the phone's body, not your body.
  3. Practice recording all four accelerations while hula hooping. You will need to press the record button, place the phone in your pocket, hula hoop for slightly more than one minute, take the phone out of your pocket, and press the record button again to stop the recording.
  4. Use the "crop" feature to crop the length of your data to exactly one minute. Make sure you remove any parts at the beginning or end of the recording when you were handling the phone. These parts of the data may look irregular or spiky on the graph. You only want to keep the part in the middle when you were rotating your hips, which should show a regular pattern like in Figure 5.
    Graph of the acceleration experienced by a hula hoop

    An example graph of acceleration during hula hooping shows a minimum acceleration of -5.2, an average acceleration of -0.4 and a max acceleration of 5.7 meters per second squared. This range of positive and negative acceleration is shown in the graph where changes in acceleration are shown as large spikes that repeat and stay between the values of 6 and -6.

    Figure 5. An example graph that shows data recorded with Google's Science Journal while hula hooping. The x-axis of the graph shows time in minutes:seconds and the y-axis shows acceleration in meters per second squared. This graph shows data from the X accelerometer, but you can also view the graphs recorded for the other three accelerometers.

  5. Once you have practiced using the app while hula hooping, follow the same procedure described in the "Testing the Performance of the Different Hula Hoops" section of the procedure. In addition to having a friend count the number of turns the hula hoop makes for each trial, use Science Journal to record all four accelerations during the trial. Make sure you keep your hula hooping style constant for the entire minute, or the pattern on the graph may change.
  6. Look at the graphs of the four different accelerations. Pick the one that shows the most obvious periodic pattern, where it will be easiest to count peaks in the graph (the four graphs will all look slightly different; some might be spikier or smoother than others). Each repetition of the same pattern, or period, represents one complete rotation of your hips. If you count the number of peaks that occur in one minute, that will tell you how many times your hips rotated in one minute (remember that the phone is attached to your hips, not the hula hoop). Add rows to your data table to record this number. Is it the same as the number of turns the hula hoop made in one minute? In other words, do your hips and the hula hoop rotate at exactly the same speed? Or is one faster than the other? Does this answer change for the different hula hoops you made? How does this relate to whether you find it easier or harder to use certain hoops? Note: if it is too difficult to count the number of peaks in one minute on the graph, you can record for a shorter period of time. For example, record for 15 seconds and then multiply the number of peaks by 4 to calculate the number of turns in one minute (15×4=60).


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If you are injured in an accident, suffer a stroke, heart attack, or loss of a limb, or are born with conditions that make it difficult to move your body, then you will often be cared for by a physical therapist. Physical therapists review a patient's medical history, test and measure his or her physical condition (things like range of motion, strength, flexibility, balance, coordination, muscle function), and then develop a treatment plan to meet some physical goals. They coach, motivate, and educate the patient to follow the plan and work on therapies that will restore, maintain, or promote physical fitness and health. Physical therapists also act as advocates, bringing a patient's health needs to the attention of other workers on a patient's healthcare team, such as physicians, speech therapists, or respiratory therapists. Read more


  • Make a bigger range of hula hoops — for example, four different sizes of hoops or four different weights — and analyze the relationship between the speed and the chosen variable (size or speed) graphically.
  • Analyze if different types of clothing affect the speed at which the hula hoop rotates around the waist or arm.

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